The present invention relates to a tandem press system that is configured so that a workpiece can be transferred from an upstream press to a downstream press disposed in a workpiece transfer direction using a workpiece transfer device, and a tool mounted on the workpiece transfer device can be replaced using a tool replacement device, and a tool replacement method.
A tandem press system that includes a plurality of presses disposed in a workpiece transfer direction processes a workpiece using each press while transferring the workpiece from the upstream press to the downstream press using a workpiece transfer device. The workpiece transfer device holds the workpiece using a tool. The tool is generally a unit formed by disposing a workpiece holding means (e.g., a plurality of vacuum suction cups) depending on the shape and the weight of the workpiece. The tool is removably mounted on the workpiece transfer device via a crossbar. Specifically, the tool is mounted on or removed from the workpiece transfer device (coupling/holding section) by mounting or removing the crossbar on or from the coupling/holding section of the workpiece transfer device.
It is necessary to replace a die when changing the press target product (product). The shape, the size, and the weight of the workpiece (material) may also change. In this case, it is necessary to replace the tool of the workpiece transfer device that has been used for the current press operation (hereinafter referred to as “current tool”) with a tool that is used for the subsequent press operation (hereinafter referred to as “subsequent tool”). A tool replacement device is used to replace the crossbar mounted with the current tool (hereinafter referred to as “current crossbar”) with the crossbar mounted with the subsequent tool (hereinafter referred to as “subsequent crossbar”). The tool replacement operation includes replacing the current crossbar with the subsequent crossbar mounted with the subsequent tool outside the press system. Note that the current tool may be removed from the current crossbar, and the subsequent tool may be mounted on the current crossbar.
A synchronous transfer-type tool replacement device that is synchronized with die transfer (related-art example 1) (e.g., JP-A-2004-50290), and an independent transfer-type tool replacement device (related-art example 2) (e.g., JP-A-2005-161379) have been known.
In the related-art example 1, a tool replacement device (12) that includes a rotary lever is rotatably mounted on a slide table (bolster). The tool replacement device (12) is transferred to the external space in synchronization with transfer of a bolster for die replacement. Specifically, the rotary lever is pulled upright, and the current crossbar is received. The tool replacement device is moved toward the bolster, and the bolster is transferred to the external space. Specifically, the current die and the current crossbar are transferred in synchronization.
The die that has been used for the current press operation (hereinafter referred to as “current die”) is replaced with a die that is used for the subsequent press operation (hereinafter referred to as “subsequent die”) in the external space, and the current crossbar is replaced with the subsequent crossbar. The subsequent crossbar is then transferred in synchronization with transfer of the bolster (die) into the press. The rotary lever is then pulled apart from the bolster, and the subsequent crossbar is delivered to the workpiece transfer device (coupling/holding section). The rotary lever is then rotated into a horizontal state.
JP-A-2004-50290 states that this tool replacement device does not hinder access to the press. However, since it is necessary to always support the tool replacement device 12 (e.g., rotary lever) in a horizontal state, it is difficult to employ the related-art example 1 for a tandem press system in which the pitch (inter-press pitch) between the upstream press and the downstream press is small.
In the related-art example 2, a truck is provided on a rail (r1, r2) that extends from the inter-press space to the external space, and a receiving stage (3) that receives a crossbar (cb) is mounted on the truck (1). In order to prevent staggering or a tilt when the truck has a small width and a large height, the position (posture) of the truck (receiving stage) with respect to the rail is stabilized by utilizing a plurality of rollers (r01, r02, r03). JP-A-2005-161379 states that the inter-press transfer device can smoothly transfer the crossbar (cb) to the external space even if the inter-press pitch is small.
JP-A-2005-161379 does not disclose the relationship with a workpiece transfer device, a crossbar replacement operation, and a die replacement operation. It is conjectured that a tool bar is replaced as follows using the inter-press transfer device. Specifically, the inter-press transfer device (receiving stage (truck)) in an empty state is transferred from the external space to the inter-press space, and the current crossbar is delivered to the receiving stage from the workpiece transfer device. The inter-press transfer device is then transferred to the external space. The current crossbar is removed, from the receiving stage in the external space, and the subsequent crossbar is mounted on the receiving stage. The inter-press transfer device is then transferred from the external space to the inter-press space, and the subsequent crossbar is delivered to the workpiece transfer device in an empty state. The inter-press transfer device is then transferred to the external space.
The related-art example 1 aims at facilitating access to the press, and the related-art example 2 aims at dealing with a small inter-press space pitch. However, the related-art examples 1 and 2 are silent about an improvement in productivity of the entire tandem press system and implementation of a quick tool replacement operation. Specifically, the related-art examples 1 and 2 are not aware of, or do not suggest, the following problems.
Productivity is improved by implementing a quick tool replacement operation. In the related-art example 1, since the die replacement operation and the tool replacement operation are sequentially performed in time series, it is difficult to promote implement a quick tool replacement operation due to the relationship with the die replacement operation. Since it is necessary to move the rotary lever (replacement device 12) relative to the bolster (table), the tool replacement operation takes time. The rotation operation also increases the tool replacement time. Moreover, since the press side space (side opening) becomes narrow, productivity is not improved even if access to the press is facilitated. Since the rotary lever (replacement device 12) is transferred to the external space together with the bolster, the die replacement operation in the external space and the subsequent tool replacement operation take time the operations become difficult) due to the mechanical configuration. Moreover, the tool cannot be replaced without replacing the die.
According to the related-art example 2 (i.e., linear travel example), the transfer speed can be relatively increased as compared with the related-art example 1 (rotation and linear travel of the heavy bolster). However, the truck (receiving stage) must be caused to make two round trips between the external space and the inter-press space in order to replace the tool. Moreover, the subsequent crossbar cannot be mounted without removing the current crossbar from the inter-press transfer device (receiving stage). This makes the operation complex, and a mistake may easily occur. Therefore, the tool replacement time increases.